Combustion chambers, in which hydrocarbon fuels such as natural gas or other gaseous hydrocarbons such as methane are burned in the presence of oxygen, are well known and have a variety of applications, including the generation of power from heat energy produced during combustion.
Combustion of hydrocarbon fuels in the presence of oxygen results in either complete combustion to give carbon dioxide (CO2) and water (H2O), or partial oxidation to give carbon monoxide (CO), hydrogen (H2) and a range of other products depending on the conditions employed. The partial oxidation of hydrocarbon fuels to produce a mixture of carbon monoxide and hydrogen gas provides the substrates for further reactions to produce diesel fuel, ammonia, hydrogen and/or methanol, as well as other fuels and chemicals. For these purposes the mixture of carbon monoxide and hydrogen gas produced from partial combustion of hydrocarbon fuels is known as ‘synthesis gas’.
The total combustion of methane is represented by the following reaction:CH4+2O2→CO2+2H2O ΔH=−802 kJ/mol
In contrast, the partial combustion of methane in the presence of oxygen to produce synthesis gas is represented by the following reaction:CH4+½O2→CO+2H2 ΔH=−35.9 kJ/mol
Synthesis gas is also commonly produced by “reforming” reactions whereby hydrocarbon fuels such as natural gas, methane or other gaseous hydrocarbons are converted into synthesis gas. Two types of reforming reaction are known: steam reforming is a reaction between methane and water to form synthesis gas, whilst dry reforming is a reaction between methane and carbon dioxide to produce synthesis gas. The reforming reactions are represented by the following equations:CH4+H2O→CO+3H2 ΔH=207 kJ/mol (steam reforming)CH4+CO2→2CO+2H2ΔH=247 kJ/mol (dry reforming).
In recent times, catalytic conversion of methane to synthesis gas by partial combustion or reforming has been favoured over non-catalytic conversion because the former takes place at lower temperatures. In the case of partial combustion, the lower temperatures consequently produce lower emissions of nitrogen oxides that have a detrimental impact on the environment.
In catalytic systems the catalyst is typically supported on an inert support such as silica or alumina and the supported catalyst is maintained in a reaction chamber. U.S. Pat. No. 6,235,262 describes a catalytic system whereby hydrogen rich gas produced in the reaction chamber is transferred to a turbine to drive the turbine and produce rotational shaft power. The present invention aims to provide an alternative to existing synthesis gas production facilities.
A reference herein to a patent document or other matter which is given as prior art is not to be taken as an admission that that document or matter was known or that the information it contains was part of the common general knowledge in any country as at the priority date of any of the claims of this application.
Throughout the description and claims of this specification, the word “comprise” and variations of the word, such as “comprising” and “comprises”, is not intended to exclude other additives, components, integers or steps.